Adipose tissue consists of an easily isolatable stroma, or a form of connective tissue from which the adult stem cells can be harvested. The stem cells specifically harvested from adipose tissue are referred to as processed lipoaspirate (PLA) cells as they are separated from other fats within the adipose tissue. These PLAs hold much hope for stem cell research as they maintain their multi-potency through adulthood. PLAs can differentiate into osteogenic, adipogenic, myogenic, and chondrogenic lineages, very much similar to mesenchymal stem cells [1]. The advantages of using adipose tissue as a source of stem cells are plentiful. Some of the major problems faced by researchers working with mesenchymal stem cells are low cell harvests, high mortality in vitro, and patient discomfort during extraction. PLAs may prove to be the answer to all of these problems. Aside from serving as a reservoir of multipotent adult stem cells, PLA's most important attribute is their similar potency to those of mesenchymal stem cells [2]. The most important use of these attributes is towards regenerative medicine and disease control. Extraction of PLAs from a patient's own fat can provide a source of stem cells that can be used for tissue regeneration that would not cause an immune response compared to cells used from other sources [3].
One of the main avenues for use of these stem cells is within regenerative medicine. In order for stem cells to fit the criteria necessary for use in regenerative medicine, they must be found in abundant quantities, harvested by a minimally invasive procedure, differentiated along multiple lineages, safely and effectively transplanted, and manufactured according to Good Manufacturing Practice guidelines. Mesenchymal stem cells are mostly separated from bone marrow extract which is a very painful process that has a very low success rate. PLAs may prove to be the answer to all of these problems. The advantages of using adipose tissue as a source of stem cells are plentiful.
Studies have also shown that along with providing more PLAs, stem cells that are isolated from lipoaspirate are also easier to grow in vitro [6]. However, the PLAs most important attribute is the fact that they are similar in potency to those of mesenchymal stem cells; they differentiate at similar rates compared to those extracted from bone marrow and show the same surface markers even when extracted from the same host [6]. The most important use of these PLAs is as a source for regenerative medicine, tissue engineering, and disease control [6]. Extraction of PLA's from a patient's own fat can provide a source of stem cells that can be used for tissue regeneration that would not generate an immune response compared to cells used from other sources [3]. For example, these multipotent cells have the potential to aid in cardiac tissue regeneration for patients with chronic heart disease [5]. In fact, PLAs can be used for the any of the potential cell lines, thus allowing for disease control treatments that lack better treatment options.
Currently, the products that are on the market concerning lipoaspirate are such that they process the tissue to separate the adipose tissue into different kinds of fat, rather than to isolate a solution of PLA's. Products that were analyzed using the ‘House of Quality’ technique were the Aquavage™ product, Lipivage™ product, StemSource™ product, and the traditional method of centrifugation after liposuction [4].
The Aquavage product, a product by M.D. Resource, processes the incoming flow of adipose tissue and separates emulsified fat tissue in order to transfer the fat back to the patient for reconstruction. This disposable, two liter lipoaspirate canister consists of two main inputs on the top of the canister [5]. The first opening is to the aspirator, which supplies the vacuum force, while the second input is to the cannula which delivers the fat, oil, anesthetic, and stem cell mixture. As the Aquavage product does not contain a filter of the specifications required for the separation of the stem cell mixture that is desired, use of the Aquavage to harvest stem cells would not eliminate the processing of the stem cells from the fat mixture. The Aquavage system also has a downfall in its design in that it has no damping of the incoming fluid, so the speed of the fluid causes disruption of the floating solution.
The Lipivage™ product provides a similar system but within a syringe. This product is used as a one-time fat harvesting system designed to filter intact fat cells. Its main use is to provide the plastic surgeon with a quick method to transfer fat within the patient for body resculpture [6]; however, the filter within this system fails to separate the stem cells, thus allowing them to be injected back into the body.
The StemSource product is more a process for separation rather than a complete device used on site. Currently, StemSource product is supplied with a bag in which the entire fat solution is frozen and sent to an outside lab to process. The separated stem cells are then frozen and kept in a ‘bank’ until further need from the patient [7]. As innovative as this method is, it does not provide a quick and efficient method of separation and processing.
Finally, the traditional method of separation, centrifugation, suffers from time needed to perform the separation and the lack of efficacy for separation. The adipose tissue must leave the operation room to another lab to get processed [7]. If the doctor wishes to cut down on time and do the centrifugation on site, there are extreme costs due to the large scale centrifuge needed.
It can be seen that all competitive products have features and drawbacks when it comes to the separation of PLAs from lipoaspirate derived during the liposuction process.